Testing metal articles



Nov. 30, 1937.

H. L. PETTERSSON 2,100,977

TESTING METAL ARTICLES Filed July 15,v 1935 2 Sheets-Sheet 1' (L3 C2 I ism/0mm Nov. 30, 1937. H. PET;I'ERSSON TESTING METAL ARTICLES Filed July 15, 1955 2 Sheets-Sheet 2 Fig. 2.

E f zo gwumtov Patented Nov. 30, 1931 UNITED STATES 2.100.911 TESTING METAL ARTICLES Hjalmar Leonard Pettersson, Stockholm, Sweden,

assignor to Patentaktiebolaget Ambia, Stockholm, Sweden Application July 15, 1935, Serial No. 31,529 In Sweden July 21, 1934 14 Claims. .(Cl. 194-100) The present invention relates to a method of and means for testing metal articles, especially coins and tokens, to determine whether they are genuine or spurious or whether or not they are 5 made of a particular known material.

The invention consists essentially in the provision of a spectrum corresponding to the metal or .alloy of which the metal article, token or coin is made, andin utilizing certain predetermined l ranges of wave lengths of this spectrum to in-' fluence a distributing relay. As it is known, a numberof different methods can be used to produce such a spectrum. One simple method consists in establishing contact between an electrode 5 of some suitable material and the coin or article to be tested, the electrode and coin being so disposed as to be included in the same electric circuit, and then separating the electrode and coin so that,-under certain conditions, an arc is pro- 2 0 duced between the coin and the electrode. The light from the arc passes through a-spectroscope containing a slit of suitable setting, through which slit only light waves within certain predetermined ranges .of wave lengths can pass. 25 The light which is in this way passed through the slit may influence a light-sensitive relay which in turn controls the disposition of the coin or otherwise indicates the result of the test.

The invention will now be more fully described so with reference to the accompanying drawings, which illustrate by way of example, but which are by no means limitative, preferred manners of carrying out the invention. V

Figure 1 is a diagrammatic view of a testing 35 apparatus illustrating the principle and man.-

ner of operation of the method andmeans of the present invention.

Figure 2 is a perspective view of one mechanical embodiment of the invention.

40 In Figure 1 the reference numeral I indicates the coin or otherarticle to be tested. Bearing against the coin there is a contact'2 connected to one of the poles of a currentsource. The 09- posite pole of the source is connected through 45 a choke coil D and a series resistance 'RI to an electrode E. If the ,electrode is moved toward the coin, or vice versa, so that the circuit 1), RI,

E, I', 2 is closed, and thereupon is removed a slight distance, an are 3 is produced between the electrode E and the coin I. The light produced by the arc is screened by a slit device SI, so that only a narrow bundle of light containing raysof all possible wave lengths reaches a condensing 55 lens MI If the distance between the lens ltll and the are 3 is equal to the focal distance .of the lens, the rays coming from the lens will be parallel and meet a prism N, which can be of any suitable construction. The embodiment of the prism illus- "trated on the drawings is of the type suggested by 'I-Iilger and is so adjusted that the directions of the in-coming and outgoing rays are nearly perpendicular to one another. After passing through the prism the light is dispersed according to its wave lengths in such a way that the rays of the same wave length are still parallel, whereas rays of different wave lengths form angles to one another. The outgoing rays meet a condensing lens M2 which refracts the rays. Near the focus of the lens M2 is placed a slit S2 provided with one or more openings OI, 02 (compare the Figure 2) which are so chosen that they exactly correspond to the positions of one or reveral of the lines characteristic of the spectrum of genuine coins.

If the coin I is a genuine one, one of sad spectrum lines will pass through the opening OI and meet a photo-cell F. Although the cell F may be of any suitable type, it may be prefer able to employ a vacuum photo-cell having an anode and a cathode on which the light-sensitive ma- -terial is provided. According to tests, such photocells, when they are not exposed to light, offer an infinitely great electrical resistance. When, however, rays fall on the sensitive material a certain electronic emission occurs which, by means of an anode voltage or a so called suction voltage, can produce an electrical signal current.

In the circuit arrangement shown in the Fi ure 1, it is assumed that the positive pole of a battery Bis connected to the anode of the photocellF, whereas the cathode is connected to a'grid of a common thermionic tube PI. The'grid is connected through a leak resistance. R2 with the negative pole of the battery B and through a grid battery bI with the cathode of the tube PI. through a relatively large resistance R3 to the positive pole of an anode battery BI and also to the grid of another thermionic tube P2. A grid battery b2 gives to the grid of the tube P2 such a biasing voltage that normally an eifective anode current passes through the anode circuit of the tube P2. This circuit contains a relay coil Qi and an anode battery B2, series-connected with one another. The relay QI controls a contact '4 included in a' circuit containing, for instance, the poles of a 220 volt-lighting main and the solenoid of a power relay-Q2. The relay Q2 The anode of the tube PI is connectedthat the hopper Cl is held in communication with the chute C3 for bad coins.

When a genuine coin is tested, the arc 3 will contain certain characteristic spectrum lines for the genuine. metal or alloy, which lines are allowed to pass through the opening OI and to efl'ect the photo-cell F. In this way a discharge current through the photo-cell F and the resistance R2 is obtained, which current causes a drop of voltage in the resistance R2 and a change in the grid voltage of the tube Pl in positive direction. If thegrid-bias voltage is'so chosen that the anode current, when the photo-cell is not exposed to light, is almost zero, the positive drop of voltage in the resistance R2 will cause an amplified anode current in the tube P] which current passesthrough the resistance R3. The drop of voltage in the resistance R3 in turn produces a drop in both the anode voltage of the tube Pl and the grid voltage of the tube P2. The increased drop of voltage in the resistance R3 thus produces a sharp reduction, preferably down to zero, of that current, which normally flows through the solenoid of the relay Ql, so that the contact 4 is'opened and the relay Q2 becomes deenergized. In this way the armature A is released and the hopper Cl is moved over to the chute C2 for genuine coins b means of a suitable springM If, on the other hand, the coin being tested is bad, the spectrum produced by the are 2 will not contain any light within that range of wave lengths which is determined by the slit opening 0| but will contain light-waves of other wave lengths which, for instance, focus at a, point 03 where the waves are screened and, thus, do not reach the photo-cell F. when the photo-cell is not exposed to light, it oiiers an infinitely great resistance and no current can pass through the resistance R2, for which reason the anode current of the tube Pl will become so weak that the anode current of the tube P2 is still operative and holds the relays Qi and Q2 energized.

Consequently, the hopper .C'l will remain just opposite the repayment chute C2.

It is, of course, assumed that the photo-cell and the spectroscope as well as the are are completely protected irom any light coming from the outside.

Figure 2 has for its object to illustrate how the inventioncan be embodied in a practical, mechanical structure. on a foot-plate I there is mounteda vertical frame 2 of insulating "material, for instance, of bakelite. The frame is provided with. a vertical coin chute 1, into which projects one arm of a two-armed lever I, 9 made of a. conducting material. The arm I is continually urged by a spring 10 into engagement with a cam disc'l I, the latter being mounted on a shaft l2 which is rotated in a clockwise direction, as indicated, by any suitable means, such as an electric motor when coins are tested. As will be understoodfrom the following description, the test of each coin requires a complete revolution of cam disc ll, each test commencing when the disc is me position approximately 90' further around in a clockwise direction than the position shown in Hg. 2.

I OppositetheendofarmLthecoLnchuteiis provided with a projecting part It, directly above which the electrode E is mounted in the frame 6 in axially displaceable position, so that the inner end or point of the same projects somewhat into the coin chute I. In the position shown in the figure, the arm 9 bears against the highest cam portion I! so that any coin which might be in the chute can freely fall into the switchable coin chute Cl, the so called hopper. The hopper Cl is pivotally mounted on the frame 6 by means of two plus I! and IQ, of which the latter carries the armature A of the electromagnet Q2. When armature A is in attracted position, the hopper Cl is held in a position above the repaymentcoin chute Cl for spurious coins, which position is shown in the figure, whereas, when the armature is not attracted, the spring It moves the armature A to its upper position so that the: coin chute Cl feeds the coin in the chute C2 for genuine coins. After the shaft l2 has turned the cam disc approximately 90 farther than the position shown in the figure, the arm 9 lies in engagement with a portion [9 of the cam of somewhat smaller radius than portion l5 whereby the. arm 8 is moved so much closer to the projecting part I; that the next coin to. fall through the chute 'I will be suspended between these two parts ready for test. As the testing begins, rotation of the disk ll brings the recess 20 opposite the arm 9, and the arm 8 pushes the; coin laterally until it bears against the inner end or point of the electrode E, whereupon a current .is .closed through the arm 8, the coin and the electrode E. Shortly thereafter, the arm Omeets the portion 2| of the'cam disc, and, due to the larger diameter of this portion, the arm 8 'is moved away from projecting part l2 removing the coin somewhat from the point of the electrode. 'In this way thearc, which isrequired for the testing, is pro duced between the coin and the point of the electrode E. The are lasts until the cam disc again approaches the position shown in the figure, at which time the arm 8 is moved so far from the projecting part ii that the-coin falls into the hopper Cl and from there into either the repayment chute C3 or the continuation chute C2, depending on the genuineness or spuriousness of the coin.-

' The slit SI is mounted in frame 6 adjacent the bottom of the chute 1, while the lenses MI and M2 and the slit device S2 are mounted on the walls inside an angular pipe 22. The prism ii is mounted in the point or comer of the angular pipe. The bottom of the pipe enters into a box 22, which is mounted on the plate 5 and contains the photo-cell F. Preferably, the in- 'termediate relay Ql can also be mounted onthe ,plate 5.

It is obvious thatthe invention is not limited to a method or apparatus in which only one slit opening OI is used or in which only coins can be tested. Apparently, one can also use several ranges of wave lengths characteristic of the genuine metal or alloy. in which event other openings, such as 02, etc.,'are provided in addition to the opening CI. The light impulses which pass article as used herein is intendedto apply to one particular species 01 articles having a certain-definite, known metallic composition, an other species being embraced within the termspurious articles", and is not intended to designate genuine articles as a general class regardless of the material from which they are made.

Having now particularly described and ascertained the nature of my invention and in what manner the same is to be performed, I declare that what I claim is:-

l. The method of distinguishing between genuine coins, tokens or like metallic articles having a definite, known composition and spurious articles of other materials which comprises the steps of producing an electric discharge having a spectrum characteristic oi the material of the article being tested, directing the spectrum of the discharge toward a light-sensitive device, pr venting all but certain predetermined wave 1e gths peculiar to the spectrum of a genuine article from aifecting said device, and utilizing the output of 'said light-sensitive device for indicating w en a genuine article is being tested.

2. The method of distinguishing between genuine coins, tokens or like metallic articles having a definite, known composition and spurious. articles of other materials which comprises the steps of producing an electric discharge having a spectrum characteristic of the material of the article being tested, directing the spectrum of the discharge toward a light-sensitive device, preventing all but certain predetermined wave lengths peculiar to the spectrum of a genuine article from affecting said device, and utilizingthe output of said light-sensitive device for-controlling the dispositionof the article being tested at the completion of the test.

3. The method of distinguishing between genuine coins, tokens or like metallic articles having a definite, known composition and spurious articles of other materials which comprises the steps of producing an electric discharge having a spectrum characteristic of the material 0! the article being tested, directing the spectrum of the discharge toward a light-sensitive device, preventing all but certain predetermined wave lengths peculiar to the spectrum of a genuine article fromafi'ecting said device, and utilizing the current generated in said light-sensitive devicefor efiecting delivery of a genuine article after being tested to a difierent destination than that to which spurious articles are delivered.

4. The method of distinguishing between genuine coins, tokens or like metallic articles having a definite, known composition and spurious articles of other materials which comprises the steps of utilizing the article being tested as one elec-, trode in the production or an electric discharge, dispersing the light produced by the discharge to form a spectrum characteristic of the material of the article being tested, directing the-spectrum thus produced oward a light-sensitive device, screening said device against all but certain predetermined wave 1 ngths peculiar to the spectrum of a genuine artic e, and utilizing the output of said light-sensitive device'for indicating when a genuine article is being tested.

, 5.7rhe method of distinguishing between gen-,- uine coins, tokens or like metallic articles having a definite, known composition and spurious'articles-oi other materials which comprises the steps of utilizing the article being tested as one electrode in the production of an electric discharge.

dispersing the light produced by the discharge to form a spectrum characteristic of the material of the article being tested, directing the spectrum thus produced toward a light-sensitive device, screening said device against all but certain predetermined wavelengths peculiar to the spectrum of a genuine article, and delivering the article being tested to one or the other of two destinationsdependent upon whether or not said lightsensitive device is aflected by the spectrum thus produced.

6. An apparatus for distinguishing between genuine coins, tokens or like metallic articles having a definite, known composition and spurious articles oi.- other materials comprising the combination or means for producing a spectrum characteristic of the material of the article being tested, a light-sensitive device disposed in the path of said spectrum, means tor preventing all but certain predetermined wavelengths peculiar to the spectrum of a genuine article from reach-- ing said device, and means controlled by the output of. said light-sensitive device for indicating when a genuine article is being tested.

7. An apparatus for distinguishing between genuine coins, tokens or like metallic articles having a definite, known composition and spurious articles of other materials comprising the combination of means for producing an electric discharge having a spectrum characteristic of the material oi the article being tested, a light-sensitive device disposed in the path of said spectrum, means for screening said device against all but certain predetermined wave lengths peculiar to the spectrum of a genuine article, and means controlled by the output of said light-sensitive'device for indicating when a genuine article is being tested,

8. An apparatus for distinguishing between genuinecoins, tokens or like metallic articles hava ing a definite, known composition and spurious articles of other materials comprising the combinationof means for producing an electric discharge having a spectrum characteristic of, the material of the article being tested, a light-sensitive device disposed in the path of said spectrum, a screen for said device having at least one slit formed therein at such position as to pass only certain predetermined wave lengths of the spec- I trum, a relay for controlling the disposition of the article beingtested after completion of the test, and means responsive to the output ofsaid lightsensitive device for controlling the operation of said relay.

9. AnaLpparatusfor distinguishing betweengenuine coins, tokens or like metallic articieshaving a definite',known composition and spurious articles of othermaterials comprising'the combination of means for producing an electric discharge including an electric circuit adapted to utilize the arti-' cle being tested as one electrode thereof, means 9 for dispersing the light produced by the dis: charge to form a spectrum characteristic of the material of the article being tested, a light sensitive device disposed in the path of the spectrum thus produced, means for preventing all but certain predetermined wave lengths of the spectrum from ailfecting said device, and means responsive to the output of said light-sensitive device Ior controlling the delivery-oi the article being tested to one or the other of two destinations at completion of the test.

10. An apparatustor distinguishing between genuine coins, tokens or likemetallic articles having a definite, known composition-and spurious articles of other materials'coinprising the combination of an electric circuit adapted to electrode and an electrically conductive'member utilize the article being tested as one electrode thereof, a second electrode for .a permanent part of said circuit, means for producirigarr elec- 5 tric discharge between said article and saiidsec- 0nd electrode, means for dispersing the light pro duced by the discharge to form a spectrum charadjacent thereto but separated therefrom so as to normally break the circuit, means for delivering the article to be tested to a position between said electrode and member and in which it is supported by and in contact with the lat- \ter, and means for eiiecting relative movement acteristic of the material ofthe article being testbetween said electrode and member so as to first ed, a light-sensitive device disposed in the path of the spectrum thus produced, a screen for said device having at least one slit formed therein at such position as to pass only certain predetermined-wave lengths of the spectrum, a relay for controlling the disposition of the article being tested after completion of the test, and means responsive to the output of said light-sensitive device for controlling the operation of said relay. 11. An apparatus for distinguishing between genuine coins, tokens or like metallic articles having a definite, known composition and spurious articles of other materials comprising the combination of an electric circuit adapted to utilize the article being tested as one electrode thereof, a second electrode forming apermanent part of said circuit, means for eflecting relative movement between said article and said second electrode toward and away from .one another so as to produce an electric discharge therebetween, meansifor dispersing the light produced by the discharge to form a spectrumcharacteristicot the material of the article being tested, a light-- sensitive -device disposed in the path of the spectrum thus produced, a screen for said device having at least one slit formed. therein at such position as to pass only certain predetermined I wave lengths or the spectrum, a relay for controlling the disposition of the article being tested after completion of the test, and means responsive to the output of said light sensitive device for e 4e controlling the operationof said relay.

12. An apparatus for distinguishing between genuine coins, tokens or like metallic articles having a definit'epknown composition and spurious articles of other materials comprising the 45 combination of an electric circuit adapted to.

utilize the article being tested as one electrode thereof, a second electrode forming a permanent part of said circuitf'means for producing an electric discharge between said article and said sec- 50 0nd electrode, means for dispersing the lightproduced by the discharge to form a spectrum characteristic oi'the material oi. the article being tested, and means including a light-sensitive device ior indicating the genuine or spurious character 55' of the article beingtested in accordance with the presence or absence 01' certain predetermined wave lengths in the spectrum thus produced.

13. An apparatus for distinguishing between o0l genuine coins, tokens or like metallic articles having a deiinite, known composition and spurious articles of other materials comprising-the combination of means for producing, an electric discharge including an electric circuit having an bring the article being tested and the electrode into contact with one another to close the circuit andthen move the same apart so as to produce anelectric discharge therebetween, means for dispersingthe light produced by the discharge a 01. the test, and means controlled-by the ouput of i said light-sensitive device for delivering the article being tested to one or the other of two destinations at completion of the test in accordance with its genuine or spurious character.

14. An apparatus for distinguishing between genuine coins, tokens or, like metallic articles having a definite, known composition and spurious articles of other materials comprising the combination of means for producing an electric discharge including an electric circuit having an electrode and an electrically conductive m'ember adjacent thereto but separated therefrom so as to normally break the circuit, means for delivering the article to be tested to a position be- -tween said electrode and member and in which it is supported by and in contact-with the latter, and means for effecting relative movement between said electrode and memberso as to first bring the article being tested and the electrode into contact with one another to close the circuit and then move the same apart so as to produce an electric discharge therebetween, means for dispersing-the light produced by the discharge to form a spectrum characteristic of the material the spectrum, means for moving said electrically conductive member out of supporting contact with the article being tested at completion of the test, and means including a distributing relay responsive to the current generated by said lightsensitive device for delivering the article being tested to one or the other or two destinations at completion oi. the test in accordance with its genuine or spurious character.-

H-lALMAR LEONA Ifl) PE'I'I'ERSSON.

so i 

